Grig, You asked me how the Demo derby works, Well it's really easy.
1) buy or find a piece of crap car and then take everything that can break, rip or just get in the way off. All the windows, all the trim, ect.
2) Weld or chain the doors shut so they will not open when you get hit.
3) Take out all but 1 gallon of gas (less to explode if your tank is hit)
4) Ram the crap out of everyone until either you can not move or everyone else is still. If you win your first section then you will move on to the finals if you can get your car running again. With me it is not worth trying to fix the car after the derby is over I just let whoever wants it take it away.
I just received some sad news for this years derby, I have to give my car to someone else as Katy (10 year old) just got into a scout camp she was waiting for, but I have to go with her so no derby this year, oh well there will always be rt. 95 to drive on.
And knowing is half the battle...